To prevent the reciprocation of a plunger by some reasons during the locking down of a plunger.

One part of bellows 21 of this bellows pump dispenser 10 is provided between a pair of reciprocation members 11, 12 of a dispenser housing. The inlet/outlet of the bellows are a valve control type and one side of these housing members is composed of a plunger operated by a finger. By a bearing element 45 provided on the plunger, the bellows are sealingly engaged with the other housing member installed on the vessel of the product to be dispensed. Thus, in the non-use state in which the plunger is pushed down perfectly, for example, in a shipping position and storage position, the bellows are sealingly engaged. A mutual operation means is provided on the housing member to lock down the dispenser under such non-use state.